Tessellation now also means tile-sized pictures made from single tiles that repeat to fill a 2D or 3D space completely without gaps or overlaps. Most people call these "M. C. Escher-style tessellations". In these tessellations, the tiles aren't square. The individual tiles are the shape of animals, people, and things. Nowadays, when we say "this is an animal tessellation", we don't see lots of little tiles making a big picture of an animal. Instead, each little tile is a little picture of an animal. The tiles cover a surface -- usually a 2D (i.e., flat) plane -- in a symmetrical way without overlapping or leaving gaps. You can see examples in the many art galleries here at Tessellations.org.